Stair Calculator With a Landing
Enter the total rise, the largest riser, the tread run and the landing size to get the risers, treads, run and stringer length of each flight and the landing's height, with each flight set beside the model code's figures.
A ready-made setup of the Stair Calculator.
Estimates for planning, not professional advice. Read the full notice.
Example: a stair with a landing
4 stair stringer board, 8 ft
- Risers in the whole stair 14 risers
- Riser height 7.714 in
- Risers below the landing 7 risers
- Risers above the landing 7 risers
- Landing height 4 ft 6 in
Estimate for planning, from what you entered and the product data shown. Check product labels and your supplier before you buy.
Your project
Enter a size to see your total.
Each product is rounded up once for the whole project, so the total can be less than the items bought alone added together. A line counted from a cut layout (sheets, boards or tiles laid out piece by piece) is counted for each item and added.
Shopping list
| Item | Size | Buy |
|---|---|---|
| Stair stringer boards, 8 ft | stair stringer board, 8 ft | 4 |
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Worked example: a stair with a landing
Show the working
- Risers of the whole stair: the total rise over the largest riser, rounded up 9 ft ÷ 7.75 in = 14 risers
- Riser height: the total rise over those risers 9 ft ÷ 14 risers = 7.714 in
- Landing height: the risers below it times the riser height 7 risers × 7.714 in = 4 ft 6 in
- Run: each flight's treads times the tread run, plus the landing depth 12 treads × 10 in + 36 in = 13 ft
Assumptions
The figures behind the example. Sourced figures link to their source below; a default is a starting value to check against your label or supplier.
| Assumption | Value | Details and changes |
|---|---|---|
| Largest riser you will allow | 7.75 in[1] | |
| Default Prefilled with the 2021 IRC maximum riser height; type a smaller number for more, lower risers. | ||
| Tread run | No default | |
| Default The depth of a tread from nosing to nosing. Check your label or supplier. | ||
| Landing depth and width | No default | |
| Default Your own landing size; a turned landing's width is yours to set. | ||
| Stringer board length | 96 in | |
| Default Common lengths; check your yard. Check your label or supplier. | ||
| Tread thickness | No default | |
| Default From your own tread board. Check your label or supplier. | ||
| Extra length for the cuts on a stringer | 0 in | |
| Default Zero unless you add one. Check your label or supplier. | ||
| Top mount | No default | |
| Default Standard: the floor above is the top tread. Flush: the top tread is on the stringer. | ||
Feet and inches, like 12' 6"
Each flight, figure by figure
Risers, riser height, treads, run, stringer length and stock board for the lower and upper flight of the example stair
| Figure | Lower flight | Upper flight |
|---|---|---|
| Risers | 7 | 7 |
| Riser height | 7.714 in | 7.714 in |
| Treads | 6 | 6 |
| Run of the flight | 5 ft | 5 ft |
| Stringer length with the cut allowance | 6 ft 3 3/4 in | 6 ft 3 3/4 in |
| Shortest listed board at or above it | 8 ft | 8 ft |
Every riser is the total rise over the risers of the whole stair. The landing is a tread level, so each flight has one tread fewer than its risers. The stringer length is geometry only; no board is sized.
The landing beside the quoted minimum
The landing's typed depth and width, and the minimum depth the model code quotes for a straight run
| Figure | Your landing | Model code figure |
|---|---|---|
| Landing depth in a straight run: within the 2021 IRC value | 36 in | 36 inModel-code (2021 IRC R311.7.6) minimum landing depth in the direction of travel for a straight run; local adopted codes differ. |
Source: [1]
The quoted minimum is for a landing on a straight run. A turned landing's width is the size you type; the calculator makes no code claim for it.
Lower flight beside the model code's figures
The lower flight's riser, tread, rise and risers set beside the figures the model code quotes, as relations
| Figure | This flight | Model code figure |
|---|---|---|
| Riser height: within the 2021 IRC value | 7.714 in | 7.75 inModel-code (2021 IRC R311.7.5.1) maximum stair riser height; local adopted codes differ. |
| Tread depth: within the 2021 IRC value | 10 in | 10 inModel-code (2021 IRC R311.7.5.2) minimum stair tread depth; local adopted codes differ. |
| Total rise of the flight: within the 2021 IRC value | 4 ft 6 in | 12 ft 7 inModel-code (2021 IRC R311.7.3) maximum vertical rise of a flight of stairs; local adopted codes differ. |
| Risers in the flight | 7 risers | 4 risersModel-code (2021 IRC R311.7.8) number of risers in a flight for which the 2021 IRC lists a handrail on one side; local adopted codes differ. |
| Tread depth, for the nosing exception | 10 in | 11 inModel-code (2021 IRC R311.7.5.3) tread depth from which the 2021 IRC text sets no nosing projection; local adopted codes differ. |
Source: [1]
A relation to a quoted figure, not a verdict. Local codes differ from the model code; check yours before you build.
Upper flight beside the model code's figures
The upper flight's riser, tread, rise and risers set beside the figures the model code quotes, as relations
| Figure | This flight | Model code figure |
|---|---|---|
| Riser height: within the 2021 IRC value | 7.714 in | 7.75 inModel-code (2021 IRC R311.7.5.1) maximum stair riser height; local adopted codes differ. |
| Tread depth: within the 2021 IRC value | 10 in | 10 inModel-code (2021 IRC R311.7.5.2) minimum stair tread depth; local adopted codes differ. |
| Total rise of the flight: within the 2021 IRC value | 4 ft 6 in | 12 ft 7 inModel-code (2021 IRC R311.7.3) maximum vertical rise of a flight of stairs; local adopted codes differ. |
| Risers in the flight | 7 risers | 4 risersModel-code (2021 IRC R311.7.8) number of risers in a flight for which the 2021 IRC lists a handrail on one side; local adopted codes differ. |
| Tread depth, for the nosing exception | 10 in | 11 inModel-code (2021 IRC R311.7.5.3) tread depth from which the 2021 IRC text sets no nosing projection; local adopted codes differ. |
Source: [1]
A relation to a quoted figure, not a verdict. Local codes differ from the model code; check yours before you build.
Questions
When do I need a landing?
The model code quotes a largest vertical rise for one flight, shown beside each flight in the tables, and a stair taller than that is split with a landing. The tool relates each flight to that figure and does not decide for you; local codes differ, so check yours.
How are the risers split between the two flights?
The whole stair has the fewest risers that keep each riser at or under your largest riser, and every riser is the total rise over that count. By default half the risers go below the landing; choose a number of risers below the landing to move it.
Why does each flight have one tread fewer than risers?
The landing is a tread level, so the lower flight ends on it, and the upper flight ends at the floor above on a standard mount. A flush mount puts the top tread on the stringer, which the Top of the upper flight choice sets.
What does a turned landing change?
The landing is a flat level at the height of its risers. A turn changes where the upper flight runs, not the risers, treads or run counted here. The landing width is the size you type, and the tool makes no code claim for it.
Local codes and amendments differ; your building department decides.
Sources (1)
-
2021 International Residential Code, Chapter 3 Building Planning (opens in new tab), International Code Council, 2021 IRC.
Code or government.
“The riser height shall be not more than 7 3/4 inches (196 mm).”
“Where the stairway has a straight run, the depth in the direction of travel shall be not less than 36 inches (914 mm).”
“The tread depth shall be not less than 10 inches (254 mm).”
“A flight of stairs shall not have a vertical rise greater than 12 feet 7 inches (3835 mm) between floor levels or landings.”
“Handrails shall be provided on not less than one side of each flight of stairs with four or more risers.”
“A nosing projection is not required where the tread depth is not less than 11 inches (279 mm).”
Checked November 12, 2026. Figures and codes change; verify with the source. Back to where this is used (Source 1)
These are summaries of what the sources say, not professional advice. Codes and product data change. Check with your building department and the product label about your own project.
Sources
- [1] International Code Council, 2021 International Residential Code, Chapter 3 Building Planning. Checked November 12, 2026. https://codes.iccsafe.org/content/IRC2021P2/chapter-3-building-planning